51 



Field Marks. Large birds of heavier flight than the Terns. Square tails and surface 

 feeding habits; not diving from the wing, and the horizontal carriage of the bill when 

 flying (See Tern, p. 55) are the best guides by which to separate the Gulls from the closely 

 allied Terns. 



Nesting. On rocky shores or cliffs near the water in various localities, depending upon 

 the species and locality. 



Distribution. Almost cosmopolitan in range and few countries are without represent- 

 atives of the subfamily. In Canada about twenty-five species are known to occur, but 

 some are only casual within the bounds of settled areas and are not discussed here. 



Though Gulls are essentially sea-birds they are at times found at 

 considerable distances from large bodies of water and flocks often follow 

 the prairie ploughman to search for insects in the newly turned furrows 

 They feed from the surface of the water, never diving, or glean from the 

 shores, beaches, or fields. 



Economic Status. Gulls eat anything in the way of animal matter, 

 fish, crustaceans, molluscs, insects, offal, and even, when opportunity offers, 

 young birds and mice. 



The amount of fish they consume is relatively unimportant, as it is 

 usually only very abundant small species occurring in great schools that 

 attract their attention; they are not patient fishers like the Herons. They 

 search low tidal shores for crabs and other shell-fish, showing considerable 

 ingenuity in breaking the hard shells and extracting the contents. The 

 food supply from these sources is economically insignificant. The Gulls 

 annually dispose of vast quantities of garbage and offal thrown into harbours 

 and waterways; they frequent agricultural land for insect food and some 

 species have been known to be instrumental in stopping mouse and other 

 small mammal and grasshopper plagues. The Gulls must be considered, 

 therefore, as beneficial and consequently should be protected, although 

 they do sometimes destroy eggs and young birds. 



Genus Rissa. Kittiwakes. 



40. Kittiwake. FR. LA MOXTETTE A. TROIS DOIGTS. Rissa tridactyla. L, 16. 

 A small or medium sized Gull of the same general coloration as the Herring Gull (See 

 p. 53). 



Distinctions. Rudimentary condition or almost total absence of a hind toe is always 

 diagnostic. 



Field Marks. Resembles so many other Gulls in general coloration that it can be 

 separated in life only by close observation of minute characters under favourable conditions. 

 In size, is smaller then the Herring and Ring-billed Gulls and larger than Bonaparte's 

 Gull. 



From the Herring and Ring-billed Gulls it differs by having black instead of flesh- 

 coloured or yellowish legs and in lacking the small terminal white spots on the black primary 

 tips. The bill is an even yellow in the adult, without the red spot of the Herring Gull 

 or the black transverse band of the Ring-billed. Juveniles resemble Bonaparte's Gull 

 very closely in having a black bill and similar colour pattern, but the forward edge of the 

 outstretched wing is mostly black instead of conspicuously white. Juvenile Kittiwakes 

 do not pass through a brown stage, as do the Herring Gulls, but resemble the adult in 

 a modified but similar coloration. 



Nesting. Makes a substantial and well-built nest of seaweed on small projections 

 from the faces of perpendicular cliffs. 



Distribution. A marine species, the Atlantic Kittiwake, occurs only casually on fresh 

 water or inland. Inhabits both sides of the Atlantic; breeding, in America, from the gulf 

 of St. Lawrence north to well into the Arctics. It should be reported on the Great Lakes 

 only upon unimpeachable evidence. 



